MICROBIAL DEGRADATION OF HAZARDOUS WASTES
BY LAND TREATMENT
Don F. Kincannon, Professor
Yia Sin Lin, Graduate Student
Bioenvironmental Engineering
School of Civil Engineering
Oklahoma State University
Stillwater, Oklahoma 74078
INTRODUCTION
The objective of hazardous waste land treatment technology is to dispose of the waste in an
environmentally safe manner by designing and operating the system to utilize the natural biological,
chemical, and physical processes in the soil for the purpose of assimilating those wastes receiving
such treatment. Assimilation of the waste by a land treatment system is a function of the waste and
soil characteristics, environmental conditions, and operation. Methodology currently used to define
the assimilative capacity of a land treatment system is not standardized. Parameters usually considered are: hydraulic loading, nutrient availability, oil and grease, known organics, acids-bases-salts,
ionic constituents, and heavy metals. However, no standard procedure has been developed for determining the allowable loading and time required for biodegradation. Therefore, the design of each
land treatment system becomes a trial and error procedure with no assurances that the design will
be successful.
If land treatment of hazardous wastes is to receive its rightful consideration, a better understanding of the biodegradation of the organic constituents must be obtained. The research effort presented
in this paper was designed to provide much needed insight in this area.
The development of kinetic constants for the assimilative capacity of a given soil under given
environmental conditions can provide the design engineer with a more scientific approach for designing land treatment systems. This could encourage the consideration of land treatment as a treatment and disposal alternative.
MATERIALS AND METHODS
Biological soil reactor studies were conducted to develop biokinetic constants and rate or half-
life information required for mathematical modeling, to determine fate of specific organics, and to
evaluate the assimilative capacity of different soil types. Three soil types ranging from clay to sandy
soils were obtained for these investigations.
Undisturbed soils were placed in glass biological soil reactors (Figure 1), and the wastes were
applied to the top and worked into the top 20 centimeters. The wastes selected for study consisted
of a DAF sludge, a SLOP OIL sludge, and a WOOD PRESERVING sludge. The biological soil
reactors were three inches in diameter with lengths of six, twelve, and eighteen inches. Provisions
were made so that the soils could be monitored at various depths.
The loading rates for the various reactors are shown in Table I. Nitrogen and phosphorus were
added so that the organics present in the wastes would be the limiting nutrient. After placing the
wastes in the reactors, the moisture content was monitored and an attempt was made to maintain
the moisture content between 20 and 30%. Also the columns were cultivated once per week to maintain aerobic conditions in the applied area of the reactors.
The sampling schedule is given in Table II. All parameters shown in Table II are not being reported in this paper. However, it was felt that it would be of interest to know the various parameters
that were monitored.
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